Influence of molecular parameters on high-strain deformation of polyethylene in the plane-strain compression. Part II. Strain recovery

Deformation and recovery behavior of the series of polyethylenes and ethylene-based copolymers with various molecular architecture and a broad range of molecular mass and its distribution, was studied. Due to the differences in molecular characteristic, this series exhibited a relatively broad range of crystallite sizes as well as crystallinity level, varying from 10 wt% up to more than 70 wt%. The samples were subjected to high-strain compression in the plane-strain conditions, above the true strain of 2. The strain recovery in the entire strain range was studied experimentally. The amount of recovered strain as well as its rate were related to molecular parameters of the material. The obtained results confirmed the common deformation scheme with four invariant cross-over points related to the activation of subsequent deformation mechanisms, including crystal fragmentation and erosion of the molecular network by chain disentanglements. This scheme was found in the past for tensile deformation. The influence of molecular network of entangled chains within amorphous component on the deformation and recovery behavior was discussed. (c) 2005 Elsevier Ltd. All rights reserved.